title: Tris(phosphinoamide)-supported uranium-cobalt heterobimetallic complexes featuring Co → U dative interactions.
abstract: A series of tris- and tetrakis(phosphinoamide) U/Co complexes has been synthesized. The uranium precursors, (η(2)-Ph2PN(i)Pr)4U (1), (η(2)-(i)Pr2PNMes)4U (2), (η(2)-Ph2PN(i)Pr)3UCl (3), and (η(2)-(i)Pr2PNMes)3UI (4), were easily accessed via addition of the appropriate stoichiometric equivalents of [Ph2PN(i)Pr]K or [(i)Pr2PNMes]K to UCl4 or UI4(dioxane)2. Although the phosphinoamide ligands in 1 and 4 have been shown to coordinate to U in an η(2)-fashion in the solid state, the phosphines are sufficiently labile in solution to coordinate cobalt upon addition of CoI2, generating the heterobimetallic Co/U complexes ICo(Ph2PN(i)Pr)3U[η(2)-Ph2PN(i)Pr] (5), ICo((i)Pr2PNMes)3U[η(2)-((i)Pr2PNMes)] (6), ICo(Ph2PN(i)Pr)3UI (7), and ICo((i)Pr2PNMes)3UI (8). Structural characterization of complexes 5 and 7 reveals reasonably short Co-U interatomic distances, with 7 exhibiting the shortest transition metal-uranium distance ever reported (2.874(3) Å). Complexes 7 and 8 were studied by cyclic voltammetry to examine the influence of the metal-metal interaction on the redox properties compared with both monometallic Co and heterobimetallic Co/Zr complexes. Theoretical studies are used to further elucidate the nature of the transition metal-actinide interaction.
authors.affiliation: Department of Chemistry, Brandeis University , 415 South Street, Waltham, Massachusetts 02454, United States.
authors.forename: J Wesley
authors.initials: JW
authors.lastname: Napoline
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Kraft
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Matson
authors.forename: Phillip E
authors.initials: PE
authors.lastname: Fanwick
authors.forename: Suzanne C
authors.initials: SC
authors.lastname: Bart
authors.forename: Christine M
authors.initials: CM
authors.lastname: Thomas